I think the E2/E2e spares carrier holds four CR123a's and a lamp. The E2 lamp is just a bulb, not a bulb/reflector assembly, so it's also small. But in any case I think you WANT to carry a spare lamp, whether it's a bulb or a reflector assembly. So for the G2 that means the larger carrier.

At a certain point maybe you want to think about a drybox (small Pelican or Otter case) instead of these tiny containers, for protecting your matches, batteries, etc.